FIG. 1 shows at 10 the general concept of expanding or extending a host parallel data bus over a serial link to make the PCI/PCIe bus (PCIe is an derivative of the PCI bus) available on an expansion system. Using this system, the host BIOS/OS will see at least one bridge or switch device 12 in a device manager (or similar program) regardless of whether or not any host expansion slots are populated with peripheral cards. If peripheral cards are present, they will also show up. Under normal conditions, the peripheral card will (should) always be visible to the host system regardless of whether a unit is in the host system, hanging on an extension card, or in an expansion unit. One such technology is the Split Bridge™ expansion technology sold by Mobility Electronics, Inc. of Scottsdale, Ariz., the teachings of which are incorporated herein by reference.
The conventional expansion bridge or switch 12 uses such techniques as clock recovery or external clock generation and alignment to ensure the correct clock-data protocol is maintained. The bridge/switch 12 also handles such things as reset, wake, and other side band signals used to ensure proper peripheral card functioning.